Abstract:

A transparent laminated bulletproof and/or splinter-proof structure
comprising three stacks of glass sheets (a, c; e, g, i; k) all connected
together by adhesive interlayers (b, d, f, h, j), in which the first
stack (a, c) is adjacent to and protrudes from the second stack (e, g,
i), which is itself adjacent to and protrudes from the third stack (k), a
liner (q, s, u) made of bulletproof and/or splinter-proof material is
bonded to the laminated structure on the free peripheral surface of the
first stack (a, c), the edge and the free peripheral surface of the
second stack (e, g, i) and the edge of the third stack (k), and a
transparent plastic sheet (m) is bonded to the liner (u) and to the free
face of the third stack (k).
A manufacturing process, the application of this laminated structure, and
a glazing comprising it.

Claims:

1. A transparent laminated structure comprising three stacks of glass
sheets all connected together by adhesive interlayers,wherein at least
part of the periphery of the laminated structure, the first stack is
adjacent to and protrudes from the second stack, which is itself adjacent
to and protrudes from the third stack,in that a liner made of bulletproof
and/of and splinter-proof material, or both, is bonded to the laminated
structure on the free peripheral surface of the first stack, the edge and
the free peripheral surface of the second stack and the edge of the third
stack,and wherein a transparent plastic sheet suitable for absorbing
energy is bonded to the liner and to the free face of the third stack.

2. The laminated structure as claimed in claim 1, wherein the liner is in
one piece.

3. The laminated structure as claimed in claim 1, wherein the liner is
made of several parts joined by adhesive.

4. The laminated structure as claimed in claim 1, wherein in said at least
part of the periphery of the laminated structure, at least one glass
sheet of said second stack protrudes from at least one other glass sheet
of said second stack, and in that the liner penetrates into the edges of
said at least one glass sheet protruding from said second stack.

5. The laminated structure as claimed in claim 1, wherein said at least
part of the periphery of the laminated structure comprises the upper side
and the two lateral sides thereof.

6. The laminated structure as claimed in claim 1, wherein its free faces
are flush.

7. The laminated structure as claimed in claim 1, wherein in said at least
part of the laminated structure, the adhesion of the liner and the
plastic sheet is maintained by a tape which covers its free edges.

8. A method for fabricating a laminated structure as claimed in claim 1,
comprisingassembling the glass block followed by passage through the
autoclave at 140-150.degree. C.,bonding the liner with an adhesive layer,
assembling the plastic sheet by means of an adhesive layer, followed by
passage through the autoclave at 105-115.degree. C. under a pressure up
to 8 bar.

9. A glazing for buildings or transport vehicles, comprising a laminated
structure as claimed in claim 1.

10. A method of stopping a shot of type 7.62.times.51 P80 armor piercing
bullets, comprising stopping said shot with a laminated structure as
claimed in claim 1, defined byimpact points that are aligned and spaced
in pairs by 120 mm, in the zone of said at least part of the periphery of
the laminated structure, the point of the first impact being midway
between the other two,bullet speeds of 820.+-.10 m/s, and byfiring angles
situated in a cone of 20.degree. to the normal of the laminated
structure.

Description:

[0001]The present invention relates to glazing that is resistant to
bullets and/or splinters and/or similar projectiles.

[0003]In the glazing zones sufficiently distant from the sides, the
ballistic resistance depends on the glass composition (number and
thickness of glass sheets). This composition is therefore defined on an
individual basis, according to the level of protection required.

[0004]In the glazing edge region, two independent mechanisms must be taken
into account.

[0005]First, the impacts of hardcore bullets (called armor piercing
bullets) are characterized by the fact that the core or the core
fragments always take the ballistic path of least energy expenditure, and
hence where the local resistance of the material is the weakest. In
bullet resistant glazings, the weakest zones, such as the joints between
pieces or sides of the glass laps, are ballistic attraction points.

[0006]According to the second mechanism, during incident impacts (firing
angle to the normal of the bullet resistant glazing), the bullet always
advances in the glass while increasing the angle of incidence by ricochet
effect. The ricochet effect is combined with the effect of the ballistic
attraction points, defining the trajectory of the bullet in the thickness
of the glazing.

[0007]Furthermore, bullet resistant glazings comprise a sheet of
non-brittle organic material on the back, having elastoplastic behavior
under high speed ballistic impacts, such as polycarbonate. This back
provides optimal ballistic efficiency when it can be deformed
isotropically to form a "dome" or "bulb".

[0008]The nearness of the sides of this sheet is a factor that may reduce
the ballistic performance of the glazing.

[0009]It is the object of the present invention to substantially improve
the ballistic resistance of the glazing.

[0010]This resistance is needed on the interior of the glazing, and can be
provided by a polycarbonate sheet, on the offset of part of the
periphery--consisting for example of the free surface of a metal
liner--and on the edge of the ballistic block--consisting for example of
a tape maintaining the adhesion of the polycarbonate and the metal
liners.

[0011]Furthermore, the shape of the glazing, in particular in its
peripheral portion, must be adapted to the mounting for which it is
intended. Thus, the thickness of the offset may be wisely adapted to be
introduced into the rebate of a car body.

[0012]It is also important, particularly in the case of sliding glazing,
that the sliding surfaces of the glazing do not have any asperities, with
any protuberances preventing the sliding of the glazing in the door seal,
for example.

[0013]These objectives are achieved by the invention which relates to a
transparent laminated bulletproof and/or splinter-proof structure
comprising three stacks of glass sheets all connected together by
adhesive interlayers, characterized in that in at least part of the
periphery of the laminated structure, the first stack is adjacent to and
protrudes from the second stack, which is itself adjacent to and
protrudes from the third stack, in that a liner made of bulletproof
and/or splinter-proof material is bonded to the laminated structure on
the free peripheral surface of the first stack, the edge and the free
peripheral surface of the second stack and the edge of the third stack,
and in that a transparent plastic sheet suitable for absorbing energy is
bonded to the liner and to the free face of the third stack.

[0014]In the context of the invention glass essentially means a mineral
glass such as a silico-sodo-calcic float glass, but also a rigid
transparent plastic of the acrylic (polymethylmethacrylate),
polycarbonate, ionomer resin type, etc.

[0015]If said second stack is thicker than the liner, it may be shaped in
three parts, possibly a "Z" shape.

[0016]In the opposite case, the liner may have a shape in two parallel
parts, obtained by eliminating the central branch of the Z.

[0017]The laminated structure is intended to be mounted in such a way that
the potential impact occurs on the side of said first stack.

[0018]According to the invention, the most vulnerable region consists of
the adhesive joining the liner to the edge of said third stack.

[0019]Thanks to the invention, this vulnerable region is at once smaller
and as far as possible from the impact zone, so that only the lowest
energy non-vulnerant core fragments reach it.

[0020]The invention consists in using metal liners--or equivalent--to
border the offset side zone of the glazing, in order to secure the most
brittle ballistic attraction zone (more brittle material at the side of
the glass lap).

[0021]Thus the vulnerant fragments deviated in the zone bordered by the
liner would necessarily be stopped by it, in particular by its part
farthest from the impact.

[0022]The fragments unaffected by the edge effect, not attracted by this
attraction zone, are stopped by the glass composition alone. Finally, the
only vulnerant fragments which have any probability of reaching the
critical zone of the joint between the liner and the edge of the third
stack have necessarily been deviated due to the attraction of the edge
zone, and therefore have had to pass through a higher glass thickness
than the undeviated shots on the glass/glass zone. In consequence, they
are less vulnerant, and will strike the final polycarbonate barrier.

[0023]Moreover, thanks to the invention, an optimal efficiency of the
deformed polycarbonate sheet is preserved by preserving an edge zone
protected by the liner and not shattered by the impact, which provides a
reliable support surface to enable the polycarbonate to be deformed into
a bulb. The ballistic steel liner must also maintain the rigidity of the
glass assembly after the first impact and force the polycarbonate to work
optimally and absorb the maximum of energy.

[0024]Furthermore, the edge of the liner adjoins the edge of said third
stack. Passage through the autoclave incurs risks of breakage by cleavage
of the glass lap (flakes) upon contact with a metal liner by
thermomechanical effect. The present invention allows the use of a bumper
scotch with a 0.38 mm one-sided polyurethane adhesive. For the ballistic
strength of the glazing, it is important for this bumper to be as thin
and as rigid as possible.

[0025]The liner is joined to the free peripheral surface of said first
stack in particular by the use of a double-sided adhesive foam tape
during passage through the autoclave, or by finishing bonding outside the
autoclave on the already laminated glazing. The adhesive used may be
acrylic, polyurethane, etc., provided that it procures very good adhesive
resistance upon the impact of a bullet, the durability required in the
conditions of use (automotive, etc.), an ability to compensate for
differences in shape between parts thanks to its foam texture, for
example.

[0026]The bulletproof and/or splinter-proof material of the liner may be
metallic (steel, etc.) or made of a composite of plastic and reinforcing
fibers (glass, aramid, etc.).

[0027]The liner is: [0028]either in a single piece, [0029]or in several
parts joined by adhesive (polyurethane, acrylic, etc.).

[0030]In a particular embodiment, in said at least part of the periphery
of the laminated structure, at least one glass sheet of said second stack
protrudes from at least one other glass sheet of said second stack, and
the liner penetrates into the edges of said at least one glass sheet
protruding from said second stack. In this case, it is also conceivable
that the liner is also penetrating with regard to said third stack.

[0031]Said at least part of the periphery of the laminated structure
preferably comprises the upper side and the two lateral sides thereof.
Thus, in a common embodiment, three of the four sides of a quadrilateral
are ballistically reinforced according to the invention.

[0032]Advantageously, the free faces of the laminated structure are flush.
The advantages are associated with the ease of assembly, the
aerodynamics, and the possibility of sliding in the case of mobile
(sliding) glazing.

[0033]In a preferred embodiment, in said at least part of the laminated
structure, the adhesion of the liner and said plastic sheet is maintained
by a tape which covers the free edges of the assembly. This tape consists
for example of the combination of thermoplastic polyurethane adhesive and
an encapsulation polyurethane, which does not soften at the assembly
temperatures in the autoclave, but at a temperature of about 180°
C. The hardness of the encapsulation PU is about 85±5 Shore A for
example. The combination of the two PUs thus combines both a rigidity in
order to correct the alignment defects of the components of the laminated
structure, and a flexibility to adapt to this lack of alignment. The
thermoplastic PU provides the bonding of the encapsulation PU with the
liner on the one hand, and with the edge of the plastic sheet on the
other hand.

[0034]The tape is also resistant to the shear to which it is subjected by
the underlying components, particularly in case of impact. It thus
performs the splinter-proof function.

[0035]An equivalent tape can be bonded to the edge of said first stack and
of the liner.

[0036]The invention further relates to a method for fabricating a
laminated structure described above, characterized in that it comprises
[0037]assembling the glass block followed by passage through the
autoclave at 140-150° C., [0038]bonding the liner by adhesives,
assembling the plastic sheet by means of an adhesive layer, followed by
passage through the autoclave at 105-115° C. under a pressure up
to 8 bar.

[0039]Other objects of the invention are [0040]a glazing for buildings
or transport vehicles, in particular automotive, such as windshield,
fixed or mobile side window or rear window, comprising a laminated
structure previously described; [0041]the application of such a laminated
structure to stop three shots of type 7.62×51 P80 armor piercing
bullets, defined by [0042]impact points that are aligned and spaced in
pairs by 120 mm, in the zone of said at least part of the periphery of
the laminated structure, the point of the first impact being midway
between the other two, [0043]bullet speeds of 820±10 m/s, and by
[0044]firing angles situated in a cone of 20° to the normal of the
laminated structure.

[0045]The invention will be better understood in light of the example that
follows with reference to the single FIGURE appended, schematically
showing a cross section of a laminated structure according to the
invention.

[0046]The table below gives the composition of all the components of a
laminated structure according to the invention, their dimensions, and,
for some of these dimensions, the ranges suitable for various feasible
applications.

[0057]The liners s and u are then joined by the interlayer adhesives r, w,
t, v.

[0058]l, m, n and o are assembled and the assembly then introduced into
the autoclave at 110° C. under a pressure up to 8 bar.

[0059]The laminated structure obtained resists all shots performed as
follows: [0060]laminated structure: specimen 500×200 mm;
[0061]three shots of armor piercing bullets 7.62×51 P80;
[0062]impact points that are aligned and spaced in pairs by 120 mm in the
peripheral zone according to the glazing invention; [0063]the point of
the first impact being midway between the other two; [0064]speed
820±10 m/s; [0065]firing angles situated in a cone of 20° to
the normal of the laminated structure.

[0066]A glazing that is different from that of the invention by the fact
that the liner q is penetrating, and by the absence of the liners s and
u, is perforated by the second impact in more than 50% of cases.